Freddie Mac (FRE) today announced that its CEO, David Moffett, is resigning just six months after being named to the post. Moffett indicated that he wants to return to a role in the financial services sector. The board of directors is working with the Federal Housing Finance Agency (FHFA) to appoint a successor to Moffett. Freddie Mac, the No. 2 U.S. mortgage finance co. into conservatorship,  was established by Congress in 1970 to provide liquidity, stability and affordability to the nation’s residential mortgage markets.